In an information apparatus, such as a notebook computer or a mobile phone, a keyboard is provided, for example, in a main body, and a display device is provided, for example, in a cover member, with the cover member provided with the display device being connected by a hinge device so that it can be opened/closed, stopped and retained at an angular position where it can be easily seen. Conventionally, such the hinge device has a pair of cams arranged with their axes matched with each other so as to allow relative rotation and movement toward and away from each other, with the cam surfaces of these cams being urged by springs to be held in intimate contact with each other; through their relative rotation, the two cams make relative movement along their axes, changing the angular relationship between the two cams (see, for example, Patent Documents 1 and 2).    Patent Document 1: JP 10-252739 A    Patent Document 2: JP 11-44142 A